Issue link: http://read.dmtmag.com/i/53575
WHAT IS biocontrol? B iological control is the suppression of pest damage through the action of one or more liv- ing natural enemies, explains Dr. Nick Mills, University of California entomologist. Natural ene- mies—such as parasitoids and predators—can reduce the potential for crop damage by attacking pests. There are three ways to implement biological control. Importation: Exotic, specialized natural ene- mies are imported from the region where the pest originated and become established. This is not suit- able for all orchard pests in the system, but is designed for use against new, invasive pests. Augmentation: The natural enemy population can be augmented through periodic release of nat- ural enemies mass-reared at an insectary. They can be released early in the season, as an inoculation, so the numbers increase, or they can be reintroduced periodically in large, inundative releases. This is the use of natural enemies as biological pesticides. Conservation: Natural enemies already in the orchard can be conserved by modifying the orchard environment. For example, integrated mite control was established in Washington State orchards through use of more selective insecticides that were compatible with predatory mites and better timing of applications. —G. Warner Invasive pests During the past 15 years, the tree fruit industry has made increasing use of mating disruption for key pests, which has led to a reduction in pesticide use and conse- quently allowed natural enemies to provide much more effective biological control of secondary pests. There are no natural enemies in place for the new invasive pests spotted wing drosophila and the brown marmorated stinkbug yet, so growers will need to resort to pesticides, Mills said. "What we have to bear in mind as we manage these new invaders is the insecticides are going to impact all the natural enemies that are doing such a good job in manag- ing the secondary pests in our orchards, and if we're not careful, we will disrupt that biological control. The choice of insecticides is going to be really important in how much biological control you may retain in your orchards when you're managing a new invasive pest." As use of standard organophosphates, such as Guthion (azinphos-methyl), ends, growers will need to understand the potential consequences of the alternative pesticides they use, he said. "Natural enemies can be very sensitive to pesticide use, and if we have incompatible insecticides in our system, those natural enemies will struggle," he said. Many of the pesticides from new classes of chemistry are interesting to growers because they have lower mam- malian toxicity than the older pesticides and so are safer for workers, but in many cases it's not known how compatible they are with natural enemies. Natural enemies tend to be more exposed to pesticide residues than pests because they're more active and are searching across the leaves all the time, looking for hosts to attack, whereas the pests sit still and feed, he said. "We have complex orchard systems, and we have to realize that pest management is not just throwing pesti- cides at a pest," Mills said. "Those pesticides are affecting the system in complex ways. Biological control can play a much greater role for us if we have sound information to work from and if we implement that information effec- tively. It's too late to appreciate the value of biological control when you've lost it." • www.goodfruit.com GOOD FRUIT GROWER FEBRUARY 1, 2012 19 farm-credit.com | 800.827.6505 This just might be the best example of "what goes around comes around" you'll ever see. Northwest Farm Credit Services is a cooperative, which means you have a voice within the organization and we pay cash back to you. No bank does this. When we do well, we share profits with you, not third party investors. And this year Northwest FCS customer-owners will receive their largest checks ever. Getting a little payback never felt so good. PAYBACK TIME A LITTLE FOR